trees.c revision 33908
117651Speter/* trees.c -- output deflated data using Huffman coding 233908Ssteve * Copyright (C) 1995-1998 Jean-loup Gailly 317651Speter * For conditions of distribution and use, see copyright notice in zlib.h 417651Speter */ 517651Speter 617651Speter/* 717651Speter * ALGORITHM 817651Speter * 917651Speter * The "deflation" process uses several Huffman trees. The more 1017651Speter * common source values are represented by shorter bit sequences. 1117651Speter * 1217651Speter * Each code tree is stored in a compressed form which is itself 1317651Speter * a Huffman encoding of the lengths of all the code strings (in 1417651Speter * ascending order by source values). The actual code strings are 1517651Speter * reconstructed from the lengths in the inflate process, as described 1617651Speter * in the deflate specification. 1717651Speter * 1817651Speter * REFERENCES 1917651Speter * 2017651Speter * Deutsch, L.P.,"'Deflate' Compressed Data Format Specification". 2117651Speter * Available in ftp.uu.net:/pub/archiving/zip/doc/deflate-1.1.doc 2217651Speter * 2317651Speter * Storer, James A. 2417651Speter * Data Compression: Methods and Theory, pp. 49-50. 2517651Speter * Computer Science Press, 1988. ISBN 0-7167-8156-5. 2617651Speter * 2717651Speter * Sedgewick, R. 2817651Speter * Algorithms, p290. 2917651Speter * Addison-Wesley, 1983. ISBN 0-201-06672-6. 3017651Speter */ 3117651Speter 3221673Sjkh/* $FreeBSD: head/lib/libz/trees.c 33908 1998-02-28 06:08:17Z steve $ */ 3317651Speter 3433908Ssteve/* #define GEN_TREES_H */ 3533908Ssteve 3617651Speter#include "deflate.h" 3717651Speter 3817651Speter#ifdef DEBUG 3917651Speter# include <ctype.h> 4017651Speter#endif 4117651Speter 4217651Speter/* =========================================================================== 4317651Speter * Constants 4417651Speter */ 4517651Speter 4617651Speter#define MAX_BL_BITS 7 4717651Speter/* Bit length codes must not exceed MAX_BL_BITS bits */ 4817651Speter 4917651Speter#define END_BLOCK 256 5017651Speter/* end of block literal code */ 5117651Speter 5217651Speter#define REP_3_6 16 5317651Speter/* repeat previous bit length 3-6 times (2 bits of repeat count) */ 5417651Speter 5517651Speter#define REPZ_3_10 17 5617651Speter/* repeat a zero length 3-10 times (3 bits of repeat count) */ 5717651Speter 5817651Speter#define REPZ_11_138 18 5917651Speter/* repeat a zero length 11-138 times (7 bits of repeat count) */ 6017651Speter 6133908Sstevelocal const int extra_lbits[LENGTH_CODES] /* extra bits for each length code */ 6217651Speter = {0,0,0,0,0,0,0,0,1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4,5,5,5,5,0}; 6317651Speter 6433908Sstevelocal const int extra_dbits[D_CODES] /* extra bits for each distance code */ 6517651Speter = {0,0,0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,13,13}; 6617651Speter 6733908Sstevelocal const int extra_blbits[BL_CODES]/* extra bits for each bit length code */ 6817651Speter = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7}; 6917651Speter 7033908Sstevelocal const uch bl_order[BL_CODES] 7117651Speter = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15}; 7217651Speter/* The lengths of the bit length codes are sent in order of decreasing 7317651Speter * probability, to avoid transmitting the lengths for unused bit length codes. 7417651Speter */ 7517651Speter 7617651Speter#define Buf_size (8 * 2*sizeof(char)) 7717651Speter/* Number of bits used within bi_buf. (bi_buf might be implemented on 7817651Speter * more than 16 bits on some systems.) 7917651Speter */ 8017651Speter 8117651Speter/* =========================================================================== 8217651Speter * Local data. These are initialized only once. 8317651Speter */ 8417651Speter 8533908Ssteve#define DIST_CODE_LEN 512 /* see definition of array dist_code below */ 8633908Ssteve 8733908Ssteve#if defined(GEN_TREES_H) || !defined(STDC) 8833908Ssteve/* non ANSI compilers may not accept trees.h */ 8933908Ssteve 9017651Speterlocal ct_data static_ltree[L_CODES+2]; 9117651Speter/* The static literal tree. Since the bit lengths are imposed, there is no 9217651Speter * need for the L_CODES extra codes used during heap construction. However 9317651Speter * The codes 286 and 287 are needed to build a canonical tree (see _tr_init 9417651Speter * below). 9517651Speter */ 9617651Speter 9717651Speterlocal ct_data static_dtree[D_CODES]; 9817651Speter/* The static distance tree. (Actually a trivial tree since all codes use 9917651Speter * 5 bits.) 10017651Speter */ 10117651Speter 10233908Ssteveuch _dist_code[DIST_CODE_LEN]; 10333908Ssteve/* Distance codes. The first 256 values correspond to the distances 10417651Speter * 3 .. 258, the last 256 values correspond to the top 8 bits of 10517651Speter * the 15 bit distances. 10617651Speter */ 10717651Speter 10833908Ssteveuch _length_code[MAX_MATCH-MIN_MATCH+1]; 10917651Speter/* length code for each normalized match length (0 == MIN_MATCH) */ 11017651Speter 11117651Speterlocal int base_length[LENGTH_CODES]; 11217651Speter/* First normalized length for each code (0 = MIN_MATCH) */ 11317651Speter 11417651Speterlocal int base_dist[D_CODES]; 11517651Speter/* First normalized distance for each code (0 = distance of 1) */ 11617651Speter 11733908Ssteve#else 11833908Ssteve# include "trees.h" 11933908Ssteve#endif /* GEN_TREES_H */ 12033908Ssteve 12117651Speterstruct static_tree_desc_s { 12233908Ssteve const ct_data *static_tree; /* static tree or NULL */ 12333908Ssteve const intf *extra_bits; /* extra bits for each code or NULL */ 12417651Speter int extra_base; /* base index for extra_bits */ 12517651Speter int elems; /* max number of elements in the tree */ 12617651Speter int max_length; /* max bit length for the codes */ 12717651Speter}; 12817651Speter 12917651Speterlocal static_tree_desc static_l_desc = 13017651Speter{static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS}; 13117651Speter 13217651Speterlocal static_tree_desc static_d_desc = 13317651Speter{static_dtree, extra_dbits, 0, D_CODES, MAX_BITS}; 13417651Speter 13517651Speterlocal static_tree_desc static_bl_desc = 13633908Ssteve{(const ct_data *)0, extra_blbits, 0, BL_CODES, MAX_BL_BITS}; 13717651Speter 13817651Speter/* =========================================================================== 13917651Speter * Local (static) routines in this file. 14017651Speter */ 14117651Speter 14217651Speterlocal void tr_static_init OF((void)); 14317651Speterlocal void init_block OF((deflate_state *s)); 14417651Speterlocal void pqdownheap OF((deflate_state *s, ct_data *tree, int k)); 14517651Speterlocal void gen_bitlen OF((deflate_state *s, tree_desc *desc)); 14617651Speterlocal void gen_codes OF((ct_data *tree, int max_code, ushf *bl_count)); 14717651Speterlocal void build_tree OF((deflate_state *s, tree_desc *desc)); 14817651Speterlocal void scan_tree OF((deflate_state *s, ct_data *tree, int max_code)); 14917651Speterlocal void send_tree OF((deflate_state *s, ct_data *tree, int max_code)); 15017651Speterlocal int build_bl_tree OF((deflate_state *s)); 15117651Speterlocal void send_all_trees OF((deflate_state *s, int lcodes, int dcodes, 15217651Speter int blcodes)); 15317651Speterlocal void compress_block OF((deflate_state *s, ct_data *ltree, 15417651Speter ct_data *dtree)); 15517651Speterlocal void set_data_type OF((deflate_state *s)); 15617651Speterlocal unsigned bi_reverse OF((unsigned value, int length)); 15717651Speterlocal void bi_windup OF((deflate_state *s)); 15817651Speterlocal void bi_flush OF((deflate_state *s)); 15917651Speterlocal void copy_block OF((deflate_state *s, charf *buf, unsigned len, 16017651Speter int header)); 16117651Speter 16233908Ssteve#ifdef GEN_TREES_H 16333908Sstevelocal void gen_trees_header OF((void)); 16433908Ssteve#endif 16533908Ssteve 16617651Speter#ifndef DEBUG 16717651Speter# define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len) 16817651Speter /* Send a code of the given tree. c and tree must not have side effects */ 16917651Speter 17017651Speter#else /* DEBUG */ 17117651Speter# define send_code(s, c, tree) \ 17233908Ssteve { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \ 17317651Speter send_bits(s, tree[c].Code, tree[c].Len); } 17417651Speter#endif 17517651Speter 17617651Speter/* =========================================================================== 17717651Speter * Output a short LSB first on the stream. 17817651Speter * IN assertion: there is enough room in pendingBuf. 17917651Speter */ 18017651Speter#define put_short(s, w) { \ 18117651Speter put_byte(s, (uch)((w) & 0xff)); \ 18217651Speter put_byte(s, (uch)((ush)(w) >> 8)); \ 18317651Speter} 18417651Speter 18517651Speter/* =========================================================================== 18617651Speter * Send a value on a given number of bits. 18717651Speter * IN assertion: length <= 16 and value fits in length bits. 18817651Speter */ 18917651Speter#ifdef DEBUG 19017651Speterlocal void send_bits OF((deflate_state *s, int value, int length)); 19117651Speter 19217651Speterlocal void send_bits(s, value, length) 19317651Speter deflate_state *s; 19417651Speter int value; /* value to send */ 19517651Speter int length; /* number of bits */ 19617651Speter{ 19717651Speter Tracevv((stderr," l %2d v %4x ", length, value)); 19817651Speter Assert(length > 0 && length <= 15, "invalid length"); 19917651Speter s->bits_sent += (ulg)length; 20017651Speter 20117651Speter /* If not enough room in bi_buf, use (valid) bits from bi_buf and 20217651Speter * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid)) 20317651Speter * unused bits in value. 20417651Speter */ 20517651Speter if (s->bi_valid > (int)Buf_size - length) { 20617651Speter s->bi_buf |= (value << s->bi_valid); 20717651Speter put_short(s, s->bi_buf); 20817651Speter s->bi_buf = (ush)value >> (Buf_size - s->bi_valid); 20917651Speter s->bi_valid += length - Buf_size; 21017651Speter } else { 21117651Speter s->bi_buf |= value << s->bi_valid; 21217651Speter s->bi_valid += length; 21317651Speter } 21417651Speter} 21517651Speter#else /* !DEBUG */ 21617651Speter 21717651Speter#define send_bits(s, value, length) \ 21817651Speter{ int len = length;\ 21917651Speter if (s->bi_valid > (int)Buf_size - len) {\ 22017651Speter int val = value;\ 22117651Speter s->bi_buf |= (val << s->bi_valid);\ 22217651Speter put_short(s, s->bi_buf);\ 22317651Speter s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\ 22417651Speter s->bi_valid += len - Buf_size;\ 22517651Speter } else {\ 22617651Speter s->bi_buf |= (value) << s->bi_valid;\ 22717651Speter s->bi_valid += len;\ 22817651Speter }\ 22917651Speter} 23017651Speter#endif /* DEBUG */ 23117651Speter 23217651Speter 23317651Speter#define MAX(a,b) (a >= b ? a : b) 23417651Speter/* the arguments must not have side effects */ 23517651Speter 23617651Speter/* =========================================================================== 23733908Ssteve * Initialize the various 'constant' tables. 23817651Speter */ 23917651Speterlocal void tr_static_init() 24017651Speter{ 24133908Ssteve#if defined(GEN_TREES_H) || !defined(STDC) 24217651Speter static int static_init_done = 0; 24317651Speter int n; /* iterates over tree elements */ 24417651Speter int bits; /* bit counter */ 24517651Speter int length; /* length value */ 24617651Speter int code; /* code value */ 24717651Speter int dist; /* distance index */ 24817651Speter ush bl_count[MAX_BITS+1]; 24917651Speter /* number of codes at each bit length for an optimal tree */ 25017651Speter 25117651Speter if (static_init_done) return; 25217651Speter 25317651Speter /* Initialize the mapping length (0..255) -> length code (0..28) */ 25417651Speter length = 0; 25517651Speter for (code = 0; code < LENGTH_CODES-1; code++) { 25617651Speter base_length[code] = length; 25717651Speter for (n = 0; n < (1<<extra_lbits[code]); n++) { 25833908Ssteve _length_code[length++] = (uch)code; 25917651Speter } 26017651Speter } 26117651Speter Assert (length == 256, "tr_static_init: length != 256"); 26217651Speter /* Note that the length 255 (match length 258) can be represented 26317651Speter * in two different ways: code 284 + 5 bits or code 285, so we 26417651Speter * overwrite length_code[255] to use the best encoding: 26517651Speter */ 26633908Ssteve _length_code[length-1] = (uch)code; 26717651Speter 26817651Speter /* Initialize the mapping dist (0..32K) -> dist code (0..29) */ 26917651Speter dist = 0; 27017651Speter for (code = 0 ; code < 16; code++) { 27117651Speter base_dist[code] = dist; 27217651Speter for (n = 0; n < (1<<extra_dbits[code]); n++) { 27333908Ssteve _dist_code[dist++] = (uch)code; 27417651Speter } 27517651Speter } 27617651Speter Assert (dist == 256, "tr_static_init: dist != 256"); 27717651Speter dist >>= 7; /* from now on, all distances are divided by 128 */ 27817651Speter for ( ; code < D_CODES; code++) { 27917651Speter base_dist[code] = dist << 7; 28017651Speter for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) { 28133908Ssteve _dist_code[256 + dist++] = (uch)code; 28217651Speter } 28317651Speter } 28417651Speter Assert (dist == 256, "tr_static_init: 256+dist != 512"); 28517651Speter 28617651Speter /* Construct the codes of the static literal tree */ 28717651Speter for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0; 28817651Speter n = 0; 28917651Speter while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++; 29017651Speter while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++; 29117651Speter while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++; 29217651Speter while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++; 29317651Speter /* Codes 286 and 287 do not exist, but we must include them in the 29417651Speter * tree construction to get a canonical Huffman tree (longest code 29517651Speter * all ones) 29617651Speter */ 29717651Speter gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count); 29817651Speter 29917651Speter /* The static distance tree is trivial: */ 30017651Speter for (n = 0; n < D_CODES; n++) { 30117651Speter static_dtree[n].Len = 5; 30217651Speter static_dtree[n].Code = bi_reverse((unsigned)n, 5); 30317651Speter } 30417651Speter static_init_done = 1; 30533908Ssteve 30633908Ssteve# ifdef GEN_TREES_H 30733908Ssteve gen_trees_header(); 30833908Ssteve# endif 30933908Ssteve#endif /* defined(GEN_TREES_H) || !defined(STDC) */ 31017651Speter} 31117651Speter 31217651Speter/* =========================================================================== 31333908Ssteve * Genererate the file trees.h describing the static trees. 31433908Ssteve */ 31533908Ssteve#ifdef GEN_TREES_H 31633908Ssteve# ifndef DEBUG 31733908Ssteve# include <stdio.h> 31833908Ssteve# endif 31933908Ssteve 32033908Ssteve# define SEPARATOR(i, last, width) \ 32133908Ssteve ((i) == (last)? "\n};\n\n" : \ 32233908Ssteve ((i) % (width) == (width)-1 ? ",\n" : ", ")) 32333908Ssteve 32433908Sstevevoid gen_trees_header() 32533908Ssteve{ 32633908Ssteve FILE *header = fopen("trees.h", "w"); 32733908Ssteve int i; 32833908Ssteve 32933908Ssteve Assert (header != NULL, "Can't open trees.h"); 33033908Ssteve fprintf(header, 33133908Ssteve "/* header created automatically with -DGEN_TREES_H */\n\n"); 33233908Ssteve 33333908Ssteve fprintf(header, "local const ct_data static_ltree[L_CODES+2] = {\n"); 33433908Ssteve for (i = 0; i < L_CODES+2; i++) { 33533908Ssteve fprintf(header, "{{%3u},{%3u}}%s", static_ltree[i].Code, 33633908Ssteve static_ltree[i].Len, SEPARATOR(i, L_CODES+1, 5)); 33733908Ssteve } 33833908Ssteve 33933908Ssteve fprintf(header, "local const ct_data static_dtree[D_CODES] = {\n"); 34033908Ssteve for (i = 0; i < D_CODES; i++) { 34133908Ssteve fprintf(header, "{{%2u},{%2u}}%s", static_dtree[i].Code, 34233908Ssteve static_dtree[i].Len, SEPARATOR(i, D_CODES-1, 5)); 34333908Ssteve } 34433908Ssteve 34533908Ssteve fprintf(header, "const uch _dist_code[DIST_CODE_LEN] = {\n"); 34633908Ssteve for (i = 0; i < DIST_CODE_LEN; i++) { 34733908Ssteve fprintf(header, "%2u%s", _dist_code[i], 34833908Ssteve SEPARATOR(i, DIST_CODE_LEN-1, 20)); 34933908Ssteve } 35033908Ssteve 35133908Ssteve fprintf(header, "const uch _length_code[MAX_MATCH-MIN_MATCH+1]= {\n"); 35233908Ssteve for (i = 0; i < MAX_MATCH-MIN_MATCH+1; i++) { 35333908Ssteve fprintf(header, "%2u%s", _length_code[i], 35433908Ssteve SEPARATOR(i, MAX_MATCH-MIN_MATCH, 20)); 35533908Ssteve } 35633908Ssteve 35733908Ssteve fprintf(header, "local const int base_length[LENGTH_CODES] = {\n"); 35833908Ssteve for (i = 0; i < LENGTH_CODES; i++) { 35933908Ssteve fprintf(header, "%1u%s", base_length[i], 36033908Ssteve SEPARATOR(i, LENGTH_CODES-1, 20)); 36133908Ssteve } 36233908Ssteve 36333908Ssteve fprintf(header, "local const int base_dist[D_CODES] = {\n"); 36433908Ssteve for (i = 0; i < D_CODES; i++) { 36533908Ssteve fprintf(header, "%5u%s", base_dist[i], 36633908Ssteve SEPARATOR(i, D_CODES-1, 10)); 36733908Ssteve } 36833908Ssteve 36933908Ssteve fclose(header); 37033908Ssteve} 37133908Ssteve#endif /* GEN_TREES_H */ 37233908Ssteve 37333908Ssteve/* =========================================================================== 37417651Speter * Initialize the tree data structures for a new zlib stream. 37517651Speter */ 37617651Spetervoid _tr_init(s) 37717651Speter deflate_state *s; 37817651Speter{ 37917651Speter tr_static_init(); 38017651Speter 38117651Speter s->compressed_len = 0L; 38217651Speter 38317651Speter s->l_desc.dyn_tree = s->dyn_ltree; 38417651Speter s->l_desc.stat_desc = &static_l_desc; 38517651Speter 38617651Speter s->d_desc.dyn_tree = s->dyn_dtree; 38717651Speter s->d_desc.stat_desc = &static_d_desc; 38817651Speter 38917651Speter s->bl_desc.dyn_tree = s->bl_tree; 39017651Speter s->bl_desc.stat_desc = &static_bl_desc; 39117651Speter 39217651Speter s->bi_buf = 0; 39317651Speter s->bi_valid = 0; 39417651Speter s->last_eob_len = 8; /* enough lookahead for inflate */ 39517651Speter#ifdef DEBUG 39617651Speter s->bits_sent = 0L; 39717651Speter#endif 39817651Speter 39917651Speter /* Initialize the first block of the first file: */ 40017651Speter init_block(s); 40117651Speter} 40217651Speter 40317651Speter/* =========================================================================== 40417651Speter * Initialize a new block. 40517651Speter */ 40617651Speterlocal void init_block(s) 40717651Speter deflate_state *s; 40817651Speter{ 40917651Speter int n; /* iterates over tree elements */ 41017651Speter 41117651Speter /* Initialize the trees. */ 41217651Speter for (n = 0; n < L_CODES; n++) s->dyn_ltree[n].Freq = 0; 41317651Speter for (n = 0; n < D_CODES; n++) s->dyn_dtree[n].Freq = 0; 41417651Speter for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0; 41517651Speter 41617651Speter s->dyn_ltree[END_BLOCK].Freq = 1; 41717651Speter s->opt_len = s->static_len = 0L; 41817651Speter s->last_lit = s->matches = 0; 41917651Speter} 42017651Speter 42117651Speter#define SMALLEST 1 42217651Speter/* Index within the heap array of least frequent node in the Huffman tree */ 42317651Speter 42417651Speter 42517651Speter/* =========================================================================== 42617651Speter * Remove the smallest element from the heap and recreate the heap with 42717651Speter * one less element. Updates heap and heap_len. 42817651Speter */ 42917651Speter#define pqremove(s, tree, top) \ 43017651Speter{\ 43117651Speter top = s->heap[SMALLEST]; \ 43217651Speter s->heap[SMALLEST] = s->heap[s->heap_len--]; \ 43317651Speter pqdownheap(s, tree, SMALLEST); \ 43417651Speter} 43517651Speter 43617651Speter/* =========================================================================== 43717651Speter * Compares to subtrees, using the tree depth as tie breaker when 43817651Speter * the subtrees have equal frequency. This minimizes the worst case length. 43917651Speter */ 44017651Speter#define smaller(tree, n, m, depth) \ 44117651Speter (tree[n].Freq < tree[m].Freq || \ 44217651Speter (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m])) 44317651Speter 44417651Speter/* =========================================================================== 44517651Speter * Restore the heap property by moving down the tree starting at node k, 44617651Speter * exchanging a node with the smallest of its two sons if necessary, stopping 44717651Speter * when the heap property is re-established (each father smaller than its 44817651Speter * two sons). 44917651Speter */ 45017651Speterlocal void pqdownheap(s, tree, k) 45117651Speter deflate_state *s; 45217651Speter ct_data *tree; /* the tree to restore */ 45317651Speter int k; /* node to move down */ 45417651Speter{ 45517651Speter int v = s->heap[k]; 45617651Speter int j = k << 1; /* left son of k */ 45717651Speter while (j <= s->heap_len) { 45817651Speter /* Set j to the smallest of the two sons: */ 45917651Speter if (j < s->heap_len && 46017651Speter smaller(tree, s->heap[j+1], s->heap[j], s->depth)) { 46117651Speter j++; 46217651Speter } 46317651Speter /* Exit if v is smaller than both sons */ 46417651Speter if (smaller(tree, v, s->heap[j], s->depth)) break; 46517651Speter 46617651Speter /* Exchange v with the smallest son */ 46717651Speter s->heap[k] = s->heap[j]; k = j; 46817651Speter 46917651Speter /* And continue down the tree, setting j to the left son of k */ 47017651Speter j <<= 1; 47117651Speter } 47217651Speter s->heap[k] = v; 47317651Speter} 47417651Speter 47517651Speter/* =========================================================================== 47617651Speter * Compute the optimal bit lengths for a tree and update the total bit length 47717651Speter * for the current block. 47817651Speter * IN assertion: the fields freq and dad are set, heap[heap_max] and 47917651Speter * above are the tree nodes sorted by increasing frequency. 48017651Speter * OUT assertions: the field len is set to the optimal bit length, the 48117651Speter * array bl_count contains the frequencies for each bit length. 48217651Speter * The length opt_len is updated; static_len is also updated if stree is 48317651Speter * not null. 48417651Speter */ 48517651Speterlocal void gen_bitlen(s, desc) 48617651Speter deflate_state *s; 48717651Speter tree_desc *desc; /* the tree descriptor */ 48817651Speter{ 48933908Ssteve ct_data *tree = desc->dyn_tree; 49033908Ssteve int max_code = desc->max_code; 49133908Ssteve const ct_data *stree = desc->stat_desc->static_tree; 49233908Ssteve const intf *extra = desc->stat_desc->extra_bits; 49333908Ssteve int base = desc->stat_desc->extra_base; 49433908Ssteve int max_length = desc->stat_desc->max_length; 49517651Speter int h; /* heap index */ 49617651Speter int n, m; /* iterate over the tree elements */ 49717651Speter int bits; /* bit length */ 49817651Speter int xbits; /* extra bits */ 49917651Speter ush f; /* frequency */ 50017651Speter int overflow = 0; /* number of elements with bit length too large */ 50117651Speter 50217651Speter for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0; 50317651Speter 50417651Speter /* In a first pass, compute the optimal bit lengths (which may 50517651Speter * overflow in the case of the bit length tree). 50617651Speter */ 50717651Speter tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */ 50817651Speter 50917651Speter for (h = s->heap_max+1; h < HEAP_SIZE; h++) { 51017651Speter n = s->heap[h]; 51117651Speter bits = tree[tree[n].Dad].Len + 1; 51217651Speter if (bits > max_length) bits = max_length, overflow++; 51317651Speter tree[n].Len = (ush)bits; 51417651Speter /* We overwrite tree[n].Dad which is no longer needed */ 51517651Speter 51617651Speter if (n > max_code) continue; /* not a leaf node */ 51717651Speter 51817651Speter s->bl_count[bits]++; 51917651Speter xbits = 0; 52017651Speter if (n >= base) xbits = extra[n-base]; 52117651Speter f = tree[n].Freq; 52217651Speter s->opt_len += (ulg)f * (bits + xbits); 52317651Speter if (stree) s->static_len += (ulg)f * (stree[n].Len + xbits); 52417651Speter } 52517651Speter if (overflow == 0) return; 52617651Speter 52717651Speter Trace((stderr,"\nbit length overflow\n")); 52817651Speter /* This happens for example on obj2 and pic of the Calgary corpus */ 52917651Speter 53017651Speter /* Find the first bit length which could increase: */ 53117651Speter do { 53217651Speter bits = max_length-1; 53317651Speter while (s->bl_count[bits] == 0) bits--; 53417651Speter s->bl_count[bits]--; /* move one leaf down the tree */ 53517651Speter s->bl_count[bits+1] += 2; /* move one overflow item as its brother */ 53617651Speter s->bl_count[max_length]--; 53717651Speter /* The brother of the overflow item also moves one step up, 53817651Speter * but this does not affect bl_count[max_length] 53917651Speter */ 54017651Speter overflow -= 2; 54117651Speter } while (overflow > 0); 54217651Speter 54317651Speter /* Now recompute all bit lengths, scanning in increasing frequency. 54417651Speter * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all 54517651Speter * lengths instead of fixing only the wrong ones. This idea is taken 54617651Speter * from 'ar' written by Haruhiko Okumura.) 54717651Speter */ 54817651Speter for (bits = max_length; bits != 0; bits--) { 54917651Speter n = s->bl_count[bits]; 55017651Speter while (n != 0) { 55117651Speter m = s->heap[--h]; 55217651Speter if (m > max_code) continue; 55317651Speter if (tree[m].Len != (unsigned) bits) { 55417651Speter Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits)); 55517651Speter s->opt_len += ((long)bits - (long)tree[m].Len) 55617651Speter *(long)tree[m].Freq; 55717651Speter tree[m].Len = (ush)bits; 55817651Speter } 55917651Speter n--; 56017651Speter } 56117651Speter } 56217651Speter} 56317651Speter 56417651Speter/* =========================================================================== 56517651Speter * Generate the codes for a given tree and bit counts (which need not be 56617651Speter * optimal). 56717651Speter * IN assertion: the array bl_count contains the bit length statistics for 56817651Speter * the given tree and the field len is set for all tree elements. 56917651Speter * OUT assertion: the field code is set for all tree elements of non 57017651Speter * zero code length. 57117651Speter */ 57217651Speterlocal void gen_codes (tree, max_code, bl_count) 57317651Speter ct_data *tree; /* the tree to decorate */ 57417651Speter int max_code; /* largest code with non zero frequency */ 57517651Speter ushf *bl_count; /* number of codes at each bit length */ 57617651Speter{ 57717651Speter ush next_code[MAX_BITS+1]; /* next code value for each bit length */ 57817651Speter ush code = 0; /* running code value */ 57917651Speter int bits; /* bit index */ 58017651Speter int n; /* code index */ 58117651Speter 58217651Speter /* The distribution counts are first used to generate the code values 58317651Speter * without bit reversal. 58417651Speter */ 58517651Speter for (bits = 1; bits <= MAX_BITS; bits++) { 58617651Speter next_code[bits] = code = (code + bl_count[bits-1]) << 1; 58717651Speter } 58817651Speter /* Check that the bit counts in bl_count are consistent. The last code 58917651Speter * must be all ones. 59017651Speter */ 59117651Speter Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1, 59217651Speter "inconsistent bit counts"); 59317651Speter Tracev((stderr,"\ngen_codes: max_code %d ", max_code)); 59417651Speter 59517651Speter for (n = 0; n <= max_code; n++) { 59617651Speter int len = tree[n].Len; 59717651Speter if (len == 0) continue; 59817651Speter /* Now reverse the bits */ 59917651Speter tree[n].Code = bi_reverse(next_code[len]++, len); 60017651Speter 60117651Speter Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ", 60217651Speter n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1)); 60317651Speter } 60417651Speter} 60517651Speter 60617651Speter/* =========================================================================== 60717651Speter * Construct one Huffman tree and assigns the code bit strings and lengths. 60817651Speter * Update the total bit length for the current block. 60917651Speter * IN assertion: the field freq is set for all tree elements. 61017651Speter * OUT assertions: the fields len and code are set to the optimal bit length 61117651Speter * and corresponding code. The length opt_len is updated; static_len is 61217651Speter * also updated if stree is not null. The field max_code is set. 61317651Speter */ 61417651Speterlocal void build_tree(s, desc) 61517651Speter deflate_state *s; 61617651Speter tree_desc *desc; /* the tree descriptor */ 61717651Speter{ 61833908Ssteve ct_data *tree = desc->dyn_tree; 61933908Ssteve const ct_data *stree = desc->stat_desc->static_tree; 62033908Ssteve int elems = desc->stat_desc->elems; 62117651Speter int n, m; /* iterate over heap elements */ 62217651Speter int max_code = -1; /* largest code with non zero frequency */ 62317651Speter int node; /* new node being created */ 62417651Speter 62517651Speter /* Construct the initial heap, with least frequent element in 62617651Speter * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1]. 62717651Speter * heap[0] is not used. 62817651Speter */ 62917651Speter s->heap_len = 0, s->heap_max = HEAP_SIZE; 63017651Speter 63117651Speter for (n = 0; n < elems; n++) { 63217651Speter if (tree[n].Freq != 0) { 63317651Speter s->heap[++(s->heap_len)] = max_code = n; 63417651Speter s->depth[n] = 0; 63517651Speter } else { 63617651Speter tree[n].Len = 0; 63717651Speter } 63817651Speter } 63917651Speter 64017651Speter /* The pkzip format requires that at least one distance code exists, 64117651Speter * and that at least one bit should be sent even if there is only one 64217651Speter * possible code. So to avoid special checks later on we force at least 64317651Speter * two codes of non zero frequency. 64417651Speter */ 64517651Speter while (s->heap_len < 2) { 64617651Speter node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0); 64717651Speter tree[node].Freq = 1; 64817651Speter s->depth[node] = 0; 64917651Speter s->opt_len--; if (stree) s->static_len -= stree[node].Len; 65017651Speter /* node is 0 or 1 so it does not have extra bits */ 65117651Speter } 65217651Speter desc->max_code = max_code; 65317651Speter 65417651Speter /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree, 65517651Speter * establish sub-heaps of increasing lengths: 65617651Speter */ 65717651Speter for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n); 65817651Speter 65917651Speter /* Construct the Huffman tree by repeatedly combining the least two 66017651Speter * frequent nodes. 66117651Speter */ 66217651Speter node = elems; /* next internal node of the tree */ 66317651Speter do { 66417651Speter pqremove(s, tree, n); /* n = node of least frequency */ 66517651Speter m = s->heap[SMALLEST]; /* m = node of next least frequency */ 66617651Speter 66717651Speter s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */ 66817651Speter s->heap[--(s->heap_max)] = m; 66917651Speter 67017651Speter /* Create a new node father of n and m */ 67117651Speter tree[node].Freq = tree[n].Freq + tree[m].Freq; 67217651Speter s->depth[node] = (uch) (MAX(s->depth[n], s->depth[m]) + 1); 67317651Speter tree[n].Dad = tree[m].Dad = (ush)node; 67417651Speter#ifdef DUMP_BL_TREE 67517651Speter if (tree == s->bl_tree) { 67617651Speter fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)", 67717651Speter node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq); 67817651Speter } 67917651Speter#endif 68017651Speter /* and insert the new node in the heap */ 68117651Speter s->heap[SMALLEST] = node++; 68217651Speter pqdownheap(s, tree, SMALLEST); 68317651Speter 68417651Speter } while (s->heap_len >= 2); 68517651Speter 68617651Speter s->heap[--(s->heap_max)] = s->heap[SMALLEST]; 68717651Speter 68817651Speter /* At this point, the fields freq and dad are set. We can now 68917651Speter * generate the bit lengths. 69017651Speter */ 69117651Speter gen_bitlen(s, (tree_desc *)desc); 69217651Speter 69317651Speter /* The field len is now set, we can generate the bit codes */ 69417651Speter gen_codes ((ct_data *)tree, max_code, s->bl_count); 69517651Speter} 69617651Speter 69717651Speter/* =========================================================================== 69817651Speter * Scan a literal or distance tree to determine the frequencies of the codes 69917651Speter * in the bit length tree. 70017651Speter */ 70117651Speterlocal void scan_tree (s, tree, max_code) 70217651Speter deflate_state *s; 70317651Speter ct_data *tree; /* the tree to be scanned */ 70417651Speter int max_code; /* and its largest code of non zero frequency */ 70517651Speter{ 70617651Speter int n; /* iterates over all tree elements */ 70717651Speter int prevlen = -1; /* last emitted length */ 70817651Speter int curlen; /* length of current code */ 70917651Speter int nextlen = tree[0].Len; /* length of next code */ 71017651Speter int count = 0; /* repeat count of the current code */ 71117651Speter int max_count = 7; /* max repeat count */ 71217651Speter int min_count = 4; /* min repeat count */ 71317651Speter 71417651Speter if (nextlen == 0) max_count = 138, min_count = 3; 71517651Speter tree[max_code+1].Len = (ush)0xffff; /* guard */ 71617651Speter 71717651Speter for (n = 0; n <= max_code; n++) { 71817651Speter curlen = nextlen; nextlen = tree[n+1].Len; 71917651Speter if (++count < max_count && curlen == nextlen) { 72017651Speter continue; 72117651Speter } else if (count < min_count) { 72217651Speter s->bl_tree[curlen].Freq += count; 72317651Speter } else if (curlen != 0) { 72417651Speter if (curlen != prevlen) s->bl_tree[curlen].Freq++; 72517651Speter s->bl_tree[REP_3_6].Freq++; 72617651Speter } else if (count <= 10) { 72717651Speter s->bl_tree[REPZ_3_10].Freq++; 72817651Speter } else { 72917651Speter s->bl_tree[REPZ_11_138].Freq++; 73017651Speter } 73117651Speter count = 0; prevlen = curlen; 73217651Speter if (nextlen == 0) { 73317651Speter max_count = 138, min_count = 3; 73417651Speter } else if (curlen == nextlen) { 73517651Speter max_count = 6, min_count = 3; 73617651Speter } else { 73717651Speter max_count = 7, min_count = 4; 73817651Speter } 73917651Speter } 74017651Speter} 74117651Speter 74217651Speter/* =========================================================================== 74317651Speter * Send a literal or distance tree in compressed form, using the codes in 74417651Speter * bl_tree. 74517651Speter */ 74617651Speterlocal void send_tree (s, tree, max_code) 74717651Speter deflate_state *s; 74817651Speter ct_data *tree; /* the tree to be scanned */ 74917651Speter int max_code; /* and its largest code of non zero frequency */ 75017651Speter{ 75117651Speter int n; /* iterates over all tree elements */ 75217651Speter int prevlen = -1; /* last emitted length */ 75317651Speter int curlen; /* length of current code */ 75417651Speter int nextlen = tree[0].Len; /* length of next code */ 75517651Speter int count = 0; /* repeat count of the current code */ 75617651Speter int max_count = 7; /* max repeat count */ 75717651Speter int min_count = 4; /* min repeat count */ 75817651Speter 75917651Speter /* tree[max_code+1].Len = -1; */ /* guard already set */ 76017651Speter if (nextlen == 0) max_count = 138, min_count = 3; 76117651Speter 76217651Speter for (n = 0; n <= max_code; n++) { 76317651Speter curlen = nextlen; nextlen = tree[n+1].Len; 76417651Speter if (++count < max_count && curlen == nextlen) { 76517651Speter continue; 76617651Speter } else if (count < min_count) { 76717651Speter do { send_code(s, curlen, s->bl_tree); } while (--count != 0); 76817651Speter 76917651Speter } else if (curlen != 0) { 77017651Speter if (curlen != prevlen) { 77117651Speter send_code(s, curlen, s->bl_tree); count--; 77217651Speter } 77317651Speter Assert(count >= 3 && count <= 6, " 3_6?"); 77417651Speter send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2); 77517651Speter 77617651Speter } else if (count <= 10) { 77717651Speter send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3); 77817651Speter 77917651Speter } else { 78017651Speter send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7); 78117651Speter } 78217651Speter count = 0; prevlen = curlen; 78317651Speter if (nextlen == 0) { 78417651Speter max_count = 138, min_count = 3; 78517651Speter } else if (curlen == nextlen) { 78617651Speter max_count = 6, min_count = 3; 78717651Speter } else { 78817651Speter max_count = 7, min_count = 4; 78917651Speter } 79017651Speter } 79117651Speter} 79217651Speter 79317651Speter/* =========================================================================== 79417651Speter * Construct the Huffman tree for the bit lengths and return the index in 79517651Speter * bl_order of the last bit length code to send. 79617651Speter */ 79717651Speterlocal int build_bl_tree(s) 79817651Speter deflate_state *s; 79917651Speter{ 80017651Speter int max_blindex; /* index of last bit length code of non zero freq */ 80117651Speter 80217651Speter /* Determine the bit length frequencies for literal and distance trees */ 80317651Speter scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code); 80417651Speter scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code); 80517651Speter 80617651Speter /* Build the bit length tree: */ 80717651Speter build_tree(s, (tree_desc *)(&(s->bl_desc))); 80817651Speter /* opt_len now includes the length of the tree representations, except 80917651Speter * the lengths of the bit lengths codes and the 5+5+4 bits for the counts. 81017651Speter */ 81117651Speter 81217651Speter /* Determine the number of bit length codes to send. The pkzip format 81317651Speter * requires that at least 4 bit length codes be sent. (appnote.txt says 81417651Speter * 3 but the actual value used is 4.) 81517651Speter */ 81617651Speter for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) { 81717651Speter if (s->bl_tree[bl_order[max_blindex]].Len != 0) break; 81817651Speter } 81917651Speter /* Update opt_len to include the bit length tree and counts */ 82017651Speter s->opt_len += 3*(max_blindex+1) + 5+5+4; 82117651Speter Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld", 82217651Speter s->opt_len, s->static_len)); 82317651Speter 82417651Speter return max_blindex; 82517651Speter} 82617651Speter 82717651Speter/* =========================================================================== 82817651Speter * Send the header for a block using dynamic Huffman trees: the counts, the 82917651Speter * lengths of the bit length codes, the literal tree and the distance tree. 83017651Speter * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4. 83117651Speter */ 83217651Speterlocal void send_all_trees(s, lcodes, dcodes, blcodes) 83317651Speter deflate_state *s; 83417651Speter int lcodes, dcodes, blcodes; /* number of codes for each tree */ 83517651Speter{ 83617651Speter int rank; /* index in bl_order */ 83717651Speter 83817651Speter Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes"); 83917651Speter Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES, 84017651Speter "too many codes"); 84117651Speter Tracev((stderr, "\nbl counts: ")); 84217651Speter send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */ 84317651Speter send_bits(s, dcodes-1, 5); 84417651Speter send_bits(s, blcodes-4, 4); /* not -3 as stated in appnote.txt */ 84517651Speter for (rank = 0; rank < blcodes; rank++) { 84617651Speter Tracev((stderr, "\nbl code %2d ", bl_order[rank])); 84717651Speter send_bits(s, s->bl_tree[bl_order[rank]].Len, 3); 84817651Speter } 84917651Speter Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent)); 85017651Speter 85117651Speter send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */ 85217651Speter Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent)); 85317651Speter 85417651Speter send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */ 85517651Speter Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent)); 85617651Speter} 85717651Speter 85817651Speter/* =========================================================================== 85917651Speter * Send a stored block 86017651Speter */ 86117651Spetervoid _tr_stored_block(s, buf, stored_len, eof) 86217651Speter deflate_state *s; 86317651Speter charf *buf; /* input block */ 86417651Speter ulg stored_len; /* length of input block */ 86517651Speter int eof; /* true if this is the last block for a file */ 86617651Speter{ 86717651Speter send_bits(s, (STORED_BLOCK<<1)+eof, 3); /* send block type */ 86817651Speter s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L; 86917651Speter s->compressed_len += (stored_len + 4) << 3; 87017651Speter 87117651Speter copy_block(s, buf, (unsigned)stored_len, 1); /* with header */ 87217651Speter} 87317651Speter 87417651Speter/* =========================================================================== 87517651Speter * Send one empty static block to give enough lookahead for inflate. 87617651Speter * This takes 10 bits, of which 7 may remain in the bit buffer. 87717651Speter * The current inflate code requires 9 bits of lookahead. If the 87817651Speter * last two codes for the previous block (real code plus EOB) were coded 87917651Speter * on 5 bits or less, inflate may have only 5+3 bits of lookahead to decode 88017651Speter * the last real code. In this case we send two empty static blocks instead 88117651Speter * of one. (There are no problems if the previous block is stored or fixed.) 88217651Speter * To simplify the code, we assume the worst case of last real code encoded 88317651Speter * on one bit only. 88417651Speter */ 88517651Spetervoid _tr_align(s) 88617651Speter deflate_state *s; 88717651Speter{ 88817651Speter send_bits(s, STATIC_TREES<<1, 3); 88917651Speter send_code(s, END_BLOCK, static_ltree); 89017651Speter s->compressed_len += 10L; /* 3 for block type, 7 for EOB */ 89117651Speter bi_flush(s); 89217651Speter /* Of the 10 bits for the empty block, we have already sent 89317651Speter * (10 - bi_valid) bits. The lookahead for the last real code (before 89417651Speter * the EOB of the previous block) was thus at least one plus the length 89517651Speter * of the EOB plus what we have just sent of the empty static block. 89617651Speter */ 89717651Speter if (1 + s->last_eob_len + 10 - s->bi_valid < 9) { 89817651Speter send_bits(s, STATIC_TREES<<1, 3); 89917651Speter send_code(s, END_BLOCK, static_ltree); 90017651Speter s->compressed_len += 10L; 90117651Speter bi_flush(s); 90217651Speter } 90317651Speter s->last_eob_len = 7; 90417651Speter} 90517651Speter 90617651Speter/* =========================================================================== 90717651Speter * Determine the best encoding for the current block: dynamic trees, static 90817651Speter * trees or store, and output the encoded block to the zip file. This function 90917651Speter * returns the total compressed length for the file so far. 91017651Speter */ 91117651Speterulg _tr_flush_block(s, buf, stored_len, eof) 91217651Speter deflate_state *s; 91317651Speter charf *buf; /* input block, or NULL if too old */ 91417651Speter ulg stored_len; /* length of input block */ 91517651Speter int eof; /* true if this is the last block for a file */ 91617651Speter{ 91717651Speter ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */ 91817651Speter int max_blindex = 0; /* index of last bit length code of non zero freq */ 91917651Speter 92017651Speter /* Build the Huffman trees unless a stored block is forced */ 92117651Speter if (s->level > 0) { 92217651Speter 92317651Speter /* Check if the file is ascii or binary */ 92417651Speter if (s->data_type == Z_UNKNOWN) set_data_type(s); 92517651Speter 92617651Speter /* Construct the literal and distance trees */ 92717651Speter build_tree(s, (tree_desc *)(&(s->l_desc))); 92817651Speter Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len, 92917651Speter s->static_len)); 93017651Speter 93117651Speter build_tree(s, (tree_desc *)(&(s->d_desc))); 93217651Speter Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len, 93317651Speter s->static_len)); 93417651Speter /* At this point, opt_len and static_len are the total bit lengths of 93517651Speter * the compressed block data, excluding the tree representations. 93617651Speter */ 93717651Speter 93817651Speter /* Build the bit length tree for the above two trees, and get the index 93917651Speter * in bl_order of the last bit length code to send. 94017651Speter */ 94117651Speter max_blindex = build_bl_tree(s); 94217651Speter 94317651Speter /* Determine the best encoding. Compute first the block length in bytes*/ 94417651Speter opt_lenb = (s->opt_len+3+7)>>3; 94517651Speter static_lenb = (s->static_len+3+7)>>3; 94617651Speter 94717651Speter Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ", 94817651Speter opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len, 94917651Speter s->last_lit)); 95017651Speter 95117651Speter if (static_lenb <= opt_lenb) opt_lenb = static_lenb; 95217651Speter 95317651Speter } else { 95417651Speter Assert(buf != (char*)0, "lost buf"); 95517651Speter opt_lenb = static_lenb = stored_len + 5; /* force a stored block */ 95617651Speter } 95717651Speter 95817651Speter /* If compression failed and this is the first and last block, 95917651Speter * and if the .zip file can be seeked (to rewrite the local header), 96017651Speter * the whole file is transformed into a stored file: 96117651Speter */ 96217651Speter#ifdef STORED_FILE_OK 96317651Speter# ifdef FORCE_STORED_FILE 96417651Speter if (eof && s->compressed_len == 0L) { /* force stored file */ 96517651Speter# else 96617651Speter if (stored_len <= opt_lenb && eof && s->compressed_len==0L && seekable()) { 96717651Speter# endif 96817651Speter /* Since LIT_BUFSIZE <= 2*WSIZE, the input data must be there: */ 96917651Speter if (buf == (charf*)0) error ("block vanished"); 97017651Speter 97117651Speter copy_block(buf, (unsigned)stored_len, 0); /* without header */ 97217651Speter s->compressed_len = stored_len << 3; 97317651Speter s->method = STORED; 97417651Speter } else 97517651Speter#endif /* STORED_FILE_OK */ 97617651Speter 97717651Speter#ifdef FORCE_STORED 97817651Speter if (buf != (char*)0) { /* force stored block */ 97917651Speter#else 98017651Speter if (stored_len+4 <= opt_lenb && buf != (char*)0) { 98117651Speter /* 4: two words for the lengths */ 98217651Speter#endif 98317651Speter /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE. 98417651Speter * Otherwise we can't have processed more than WSIZE input bytes since 98517651Speter * the last block flush, because compression would have been 98617651Speter * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to 98717651Speter * transform a block into a stored block. 98817651Speter */ 98917651Speter _tr_stored_block(s, buf, stored_len, eof); 99017651Speter 99117651Speter#ifdef FORCE_STATIC 99217651Speter } else if (static_lenb >= 0) { /* force static trees */ 99317651Speter#else 99417651Speter } else if (static_lenb == opt_lenb) { 99517651Speter#endif 99617651Speter send_bits(s, (STATIC_TREES<<1)+eof, 3); 99717651Speter compress_block(s, (ct_data *)static_ltree, (ct_data *)static_dtree); 99817651Speter s->compressed_len += 3 + s->static_len; 99917651Speter } else { 100017651Speter send_bits(s, (DYN_TREES<<1)+eof, 3); 100117651Speter send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1, 100217651Speter max_blindex+1); 100317651Speter compress_block(s, (ct_data *)s->dyn_ltree, (ct_data *)s->dyn_dtree); 100417651Speter s->compressed_len += 3 + s->opt_len; 100517651Speter } 100617651Speter Assert (s->compressed_len == s->bits_sent, "bad compressed size"); 100717651Speter init_block(s); 100817651Speter 100917651Speter if (eof) { 101017651Speter bi_windup(s); 101117651Speter s->compressed_len += 7; /* align on byte boundary */ 101217651Speter } 101317651Speter Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3, 101417651Speter s->compressed_len-7*eof)); 101517651Speter 101617651Speter return s->compressed_len >> 3; 101717651Speter} 101817651Speter 101917651Speter/* =========================================================================== 102017651Speter * Save the match info and tally the frequency counts. Return true if 102117651Speter * the current block must be flushed. 102217651Speter */ 102317651Speterint _tr_tally (s, dist, lc) 102417651Speter deflate_state *s; 102517651Speter unsigned dist; /* distance of matched string */ 102617651Speter unsigned lc; /* match length-MIN_MATCH or unmatched char (if dist==0) */ 102717651Speter{ 102817651Speter s->d_buf[s->last_lit] = (ush)dist; 102917651Speter s->l_buf[s->last_lit++] = (uch)lc; 103017651Speter if (dist == 0) { 103117651Speter /* lc is the unmatched char */ 103217651Speter s->dyn_ltree[lc].Freq++; 103317651Speter } else { 103417651Speter s->matches++; 103517651Speter /* Here, lc is the match length - MIN_MATCH */ 103617651Speter dist--; /* dist = match distance - 1 */ 103717651Speter Assert((ush)dist < (ush)MAX_DIST(s) && 103817651Speter (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) && 103917651Speter (ush)d_code(dist) < (ush)D_CODES, "_tr_tally: bad match"); 104017651Speter 104133908Ssteve s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++; 104217651Speter s->dyn_dtree[d_code(dist)].Freq++; 104317651Speter } 104417651Speter 104533908Ssteve#ifdef TRUNCATE_BLOCK 104617651Speter /* Try to guess if it is profitable to stop the current block here */ 104733908Ssteve if ((s->last_lit & 0x1fff) == 0 && s->level > 2) { 104817651Speter /* Compute an upper bound for the compressed length */ 104917651Speter ulg out_length = (ulg)s->last_lit*8L; 105017651Speter ulg in_length = (ulg)((long)s->strstart - s->block_start); 105117651Speter int dcode; 105217651Speter for (dcode = 0; dcode < D_CODES; dcode++) { 105317651Speter out_length += (ulg)s->dyn_dtree[dcode].Freq * 105417651Speter (5L+extra_dbits[dcode]); 105517651Speter } 105617651Speter out_length >>= 3; 105717651Speter Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ", 105817651Speter s->last_lit, in_length, out_length, 105917651Speter 100L - out_length*100L/in_length)); 106017651Speter if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1; 106117651Speter } 106233908Ssteve#endif 106317651Speter return (s->last_lit == s->lit_bufsize-1); 106417651Speter /* We avoid equality with lit_bufsize because of wraparound at 64K 106517651Speter * on 16 bit machines and because stored blocks are restricted to 106617651Speter * 64K-1 bytes. 106717651Speter */ 106817651Speter} 106917651Speter 107017651Speter/* =========================================================================== 107117651Speter * Send the block data compressed using the given Huffman trees 107217651Speter */ 107317651Speterlocal void compress_block(s, ltree, dtree) 107417651Speter deflate_state *s; 107517651Speter ct_data *ltree; /* literal tree */ 107617651Speter ct_data *dtree; /* distance tree */ 107717651Speter{ 107817651Speter unsigned dist; /* distance of matched string */ 107917651Speter int lc; /* match length or unmatched char (if dist == 0) */ 108017651Speter unsigned lx = 0; /* running index in l_buf */ 108117651Speter unsigned code; /* the code to send */ 108217651Speter int extra; /* number of extra bits to send */ 108317651Speter 108417651Speter if (s->last_lit != 0) do { 108517651Speter dist = s->d_buf[lx]; 108617651Speter lc = s->l_buf[lx++]; 108717651Speter if (dist == 0) { 108817651Speter send_code(s, lc, ltree); /* send a literal byte */ 108917651Speter Tracecv(isgraph(lc), (stderr," '%c' ", lc)); 109017651Speter } else { 109117651Speter /* Here, lc is the match length - MIN_MATCH */ 109233908Ssteve code = _length_code[lc]; 109317651Speter send_code(s, code+LITERALS+1, ltree); /* send the length code */ 109417651Speter extra = extra_lbits[code]; 109517651Speter if (extra != 0) { 109617651Speter lc -= base_length[code]; 109717651Speter send_bits(s, lc, extra); /* send the extra length bits */ 109817651Speter } 109917651Speter dist--; /* dist is now the match distance - 1 */ 110017651Speter code = d_code(dist); 110117651Speter Assert (code < D_CODES, "bad d_code"); 110217651Speter 110317651Speter send_code(s, code, dtree); /* send the distance code */ 110417651Speter extra = extra_dbits[code]; 110517651Speter if (extra != 0) { 110617651Speter dist -= base_dist[code]; 110717651Speter send_bits(s, dist, extra); /* send the extra distance bits */ 110817651Speter } 110917651Speter } /* literal or match pair ? */ 111017651Speter 111117651Speter /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */ 111217651Speter Assert(s->pending < s->lit_bufsize + 2*lx, "pendingBuf overflow"); 111317651Speter 111417651Speter } while (lx < s->last_lit); 111517651Speter 111617651Speter send_code(s, END_BLOCK, ltree); 111717651Speter s->last_eob_len = ltree[END_BLOCK].Len; 111817651Speter} 111917651Speter 112017651Speter/* =========================================================================== 112117651Speter * Set the data type to ASCII or BINARY, using a crude approximation: 112217651Speter * binary if more than 20% of the bytes are <= 6 or >= 128, ascii otherwise. 112317651Speter * IN assertion: the fields freq of dyn_ltree are set and the total of all 112417651Speter * frequencies does not exceed 64K (to fit in an int on 16 bit machines). 112517651Speter */ 112617651Speterlocal void set_data_type(s) 112717651Speter deflate_state *s; 112817651Speter{ 112917651Speter int n = 0; 113017651Speter unsigned ascii_freq = 0; 113117651Speter unsigned bin_freq = 0; 113217651Speter while (n < 7) bin_freq += s->dyn_ltree[n++].Freq; 113317651Speter while (n < 128) ascii_freq += s->dyn_ltree[n++].Freq; 113417651Speter while (n < LITERALS) bin_freq += s->dyn_ltree[n++].Freq; 113517651Speter s->data_type = (Byte)(bin_freq > (ascii_freq >> 2) ? Z_BINARY : Z_ASCII); 113617651Speter} 113717651Speter 113817651Speter/* =========================================================================== 113917651Speter * Reverse the first len bits of a code, using straightforward code (a faster 114017651Speter * method would use a table) 114117651Speter * IN assertion: 1 <= len <= 15 114217651Speter */ 114317651Speterlocal unsigned bi_reverse(code, len) 114417651Speter unsigned code; /* the value to invert */ 114517651Speter int len; /* its bit length */ 114617651Speter{ 114717651Speter register unsigned res = 0; 114817651Speter do { 114917651Speter res |= code & 1; 115017651Speter code >>= 1, res <<= 1; 115117651Speter } while (--len > 0); 115217651Speter return res >> 1; 115317651Speter} 115417651Speter 115517651Speter/* =========================================================================== 115617651Speter * Flush the bit buffer, keeping at most 7 bits in it. 115717651Speter */ 115817651Speterlocal void bi_flush(s) 115917651Speter deflate_state *s; 116017651Speter{ 116117651Speter if (s->bi_valid == 16) { 116217651Speter put_short(s, s->bi_buf); 116317651Speter s->bi_buf = 0; 116417651Speter s->bi_valid = 0; 116517651Speter } else if (s->bi_valid >= 8) { 116617651Speter put_byte(s, (Byte)s->bi_buf); 116717651Speter s->bi_buf >>= 8; 116817651Speter s->bi_valid -= 8; 116917651Speter } 117017651Speter} 117117651Speter 117217651Speter/* =========================================================================== 117317651Speter * Flush the bit buffer and align the output on a byte boundary 117417651Speter */ 117517651Speterlocal void bi_windup(s) 117617651Speter deflate_state *s; 117717651Speter{ 117817651Speter if (s->bi_valid > 8) { 117917651Speter put_short(s, s->bi_buf); 118017651Speter } else if (s->bi_valid > 0) { 118117651Speter put_byte(s, (Byte)s->bi_buf); 118217651Speter } 118317651Speter s->bi_buf = 0; 118417651Speter s->bi_valid = 0; 118517651Speter#ifdef DEBUG 118617651Speter s->bits_sent = (s->bits_sent+7) & ~7; 118717651Speter#endif 118817651Speter} 118917651Speter 119017651Speter/* =========================================================================== 119117651Speter * Copy a stored block, storing first the length and its 119217651Speter * one's complement if requested. 119317651Speter */ 119417651Speterlocal void copy_block(s, buf, len, header) 119517651Speter deflate_state *s; 119617651Speter charf *buf; /* the input data */ 119717651Speter unsigned len; /* its length */ 119817651Speter int header; /* true if block header must be written */ 119917651Speter{ 120017651Speter bi_windup(s); /* align on byte boundary */ 120117651Speter s->last_eob_len = 8; /* enough lookahead for inflate */ 120217651Speter 120317651Speter if (header) { 120417651Speter put_short(s, (ush)len); 120517651Speter put_short(s, (ush)~len); 120617651Speter#ifdef DEBUG 120717651Speter s->bits_sent += 2*16; 120817651Speter#endif 120917651Speter } 121017651Speter#ifdef DEBUG 121117651Speter s->bits_sent += (ulg)len<<3; 121217651Speter#endif 121317651Speter while (len--) { 121417651Speter put_byte(s, *buf++); 121517651Speter } 121617651Speter} 1217